An MIMO (Multiple-Input Multiple-Output, Multiple-Input Multiple-Output) technology means that multiple transmit antennas and multiple receive antennas are used at a transmit end and a receive end respectively to cause that signals are transmitted and received by multiple antennas at the transmit end and the receive end, so as to improve communication quality. The MIMO technology can make full use of space resources and implement multiple-transmitting multiple-receiving by using multiple antennas, and can multiply a system channel capacity without increasing frequency spectrum resources and antenna transmit power, showing distinct advantages. Therefore, the MIMO technology is expected to be a core technology of next generation mobile communications.
An precoding (precoding) technology is a signal processing technology that is used to perform preprocessing on sending signals by using channel status information at a transmit end and aims at improving a system capacity and reducing a bit error ratio.
Ultra dense networks are considered to be a main evolution direction of the fifth generation mobile communications system. The ultra dense networks can maximally reuse frequency spectrum resources, and thereby provide a higher communication data rate for more users. However, severe inter-cell interference exists in a ultra dense network, and if not suppressed effectively, may seriously limit improvement of frequency spectrum efficiency and energy efficiency of a cellular system.
A proper design of a transmit end precoding matrix helps to make use of advantages brought by the multi-antenna technology and reduce inter-cell interference.